The present invention relates generally to a method for coupling a pin into a sleeve and, more particularly, to a method for assembling a magnetic pole piece into a fuel passage of a fuel injector.
It is well known in the automotive engine art to provide solenoid actuated fuel injectors for controlling the injection of fuel into the cylinders of an internal combustion engine. Fuel injectors generally include an internal fuel passage for fuel flow therein and a pole piece within the fuel passage which may be used to set the stroke length for the injector valve. Permanent fastening of the pole piece within the fuel passage of the injector could be accomplished by a press fit. In this case, the pole piece is slightly larger than the fuel passage, such that tight tolerancing of both components is required to achieve reasonable and consistent press loads. Alternatively, the pole piece may be assembled via a slip fit and affixed by means of a series of spot welds. Again, tight tolerances are required for both components.
Therefore, it is desirable to provide a method for assembling a magnetic pole piece into an internal fuel passage that improves the capability of or eliminates a secondary welding operation as well as relaxes tolerance control for the pole piece and the fuel passage.
In accordance with the present invention, a method is provided for assembling a magnetic pole piece into an internal fuel passage of a fuel injector. The assembly method includes the steps of: (a) providing an endoskeletal injector tube, where the injector tube provides the fuel passage for the fuel injector; (b) forming at least one depression into an outer surface of the injector tube; (c) inserting an injector valve into the injector tube; (d) inserting the pole piece into the injector tube, wherein the pole piece is adjustable thereafter; and (e) affixing the pole piece within the injector tube, where an outer surface of the pole piece is in contact with an inner surface of the injector tube corresponding to the depressions, thereby creating a spring fit between the pole piece and the tube.
For a more complete understanding of the invention, its objects and advantages, refer to the following specification and to the accompanying drawings.